ez80f92 ZiLOG Semiconductor, ez80f92 Datasheet - Page 205

• Manufacturer Part Number: ez80f92
• Description: Ez80acclaim Flash Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS015313-0508
Flash Key Register
Writing the two-byte sequence
the Flash Divider and Flash Write/Erase Protection registers. If these values are not
written by consecutive CPU I/O writes (I/O reads and memory Read/Writes produce no
effect), the Flash Divider and Flash Write/Erase Protection registers remain locked to
prevent accidental overwrites of these critical Flash control register settings. Writing a
value to either the Flash Frequency Divider register or the Flash Write/Erase Protection
register automatically relocks both of the registers again.
Table 113. Flash Key Register; (FLASH_KEY = 00F5h)
Flash Data Register
The Flash Data register stores the data values to be programmed to Flash memory through
I/O Write operations. This register is used for all I/O Write access to Flash, both individual
byte Writes and multibyte row programming.
For single-byte I/O Write operations, a single-byte Write to this I/O register programs the
data value into the single-byte location pointed to by the page, row, and column registers.
For multibyte I/O Write operations, the Flash controller autoincrements the column
address for each byte placed into this register. A maximum of 128 bytes of data can be
programmed into Flash during a multibyte I/O Write operation. The ROW_PGM bit in the
Flash Program Control register must be set to 1 prior to beginning a multibyte I/O Write
operation.
This register does not return data from Flash memory. If read, this register returns the most
recent data value written to the register.
Bit
Reset
CPU Access
Note: W = Write Only.
Bit
Position
[7:0]
FLASH_KEY
Value Description
B6h,
49h
Sequential Write operations of the values {B6h, 49h} to this
register unlock the Flash Frequency Divider and Flash Write/
Erase Protection registers.
W
7
0
B6h
,
W
6
0
49h
in immediate succession to this register unlocks
W
5
0
W
4
0
W
3
0
Product Specification
W
2
0
eZ80F92/eZ80F93
W
1
0
Flash Memory
W
0
0
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